The present invention relates to computer software utility programs, and more specifically to a machine and method for controlling the generation of dimensions, or other drawing data, while producing two dimensional (2-D) plans representing different views of a three dimensional (3-D) model with computer aided design (CAD) and computer aided manufacture (CAM) systems.
While using CAD/CAM applications it is often desirable to produce two 2-D plans representing different views of a 3-D model. Production of 2-D views from the 3-D model can be referred to as generative drafting. One of the difficulties attaching to the generative drafting process is the selection of a desirable drafting view. Once a user has selected an appropriate view, he can cause the system to transfer to a 2-D view of the dimension constraints (e.g. tolerances), or other data available with respect to the 3-D model.
In currently available CAD/CAM systems, transfer of dimensions and constraints, once requested by the user, is performed automatically by the system according to a predetermined set of rules. The rules can define which dimensions or other constraints will be shown on which view. Each dimension or other constraint can be shown on one and only one view and where each is located. If a user is dissatisfied with the presentation or location of one or more of the dimensions, they have to wait until the entire transfer is complete before being able to introduce modifications to the dimension presented. A modification can relate to a view chosen by the process algorithm, to the location on the view, or to the way a dimension is represented. While this automated process is generally acceptable with simple parts, it becomes a productivity limitation as a part grows more complex. Reworking 2-D plans to ensure that the dimensions and other constraints are located where the user would like them to be can be a fairly difficult, tedious and time consuming task, if a large number of dimensions have been transferred to one particular view and that view is overly encumbered with dimensions.
An ever increasing need for productivity improvements in the use of CAD/CAM systems has led to user requests for a more flexible dimension generation system which can allow a user to decide if and when he wishes to modify the location of dimensions and other constraints before all the dimensions are shown on the different views. There is therefore a need for providing a user with the capability to better control the dimension generation process.